Due to cost and concern over the environment, there is now a constant and growing demand to reduce energy consumption in all aspects of life. It is widely recognised that the failure to switch off lights and other appliances leads to the waste of a great deal of energy, and yet at first glance this area appears to be one of the easiest areas of waste to tackle. For example, occupancy detector switches which automatically control electrical lights are well known. However these devices are not as widely used as they could be and this may be in part because they are typically either installed in a ceiling or must replace existing light switches, and are always electrically connected to the circuit which supplies power to the lights. Such automatic controls are therefore difficult to install, and must be fitted by a qualified electrician if they are to function correctly and safely. The time and expense involved in such an installation is enough to put off many potential users, who instead continue to use wasteful manual controls.
Therefore automatic controllers which can be easily retro-fitted to existing installations would be very desirable, especially if those controllers required no wiring and a minimum of time and expertise to be spent on installation.